Method and Apparatus for Overlapping MIMO Physical Sectors

ABSTRACT

MIMO systems communicate with wireless devices. MIMO systems include directional antennas that are oriented so that the physical sectors of the antennas overlap to form areas of overlap. Some physical sectors overlap substantially while others overlap partially. The areas of overlap are oriented in unique directions. Radios are selectively coupled to the portion of the antennas to communicate with the wireless devices. The physical sectors of the antennas that are selectively coupled to the radios overlap. The radios use the antennas to communicate with the wireless devices. The antennas operate as a MIMO antenna.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority under 35U.S.C. §120 from U.S. patent application Ser. No. 11/709,431 byLastinger , file Feb. 21, 2007, which claims priority under 35 U.S.C.§119(e) from U.S. patent application 60/743,376 filed Feb. 28, 2006,each of the aforementioned applications is herein incorporated byreference.

FIELD OF THE INVENTION

Embodiments of the present invention relate to wireless communicationusing Multiple Input Multiple Output (“MIMO”) antennas and methods ofoperation.

BACKGROUND OF THE INVENTION

Wireless devices find uses in a variety of applications for example,providing communication between computers, wireless cells, clients,hand-held devices, mobile devices, and file servers. Wireless deviceswith Multiple Input Multiple Output (“MIMO”) antennas benefit fromspatial diversity and redundant signals. Noise sources may interferewith wireless devices that use MIMO antennas. Wireless communicationusing devices having MIMO antennas may substantially benefit fromselecting a MIMO physical sector and/or a MIMO virtual sector to improveperformance.

SUMMARY OF THE INVENTION

A MIMO system for communicating with a provided wireless device,according to various aspects of the present invention, includes at leastthree directional antennas and two radios. each antenna is oriented suchthat a physical sector of each antenna substantially overlaps a physicalsector of at least one other antenna thereby forming respective areas ofoverlap. A center of each area of overlap is oriented in a uniquedirection with respect to the MIMO system. Each radio selectivelycouples to one respective antenna. The physical sectors of the antennascoupled to the radios substantially overlap. The at least two radioscommunicate with the wireless device using the respective antennascoupled to each radio. The antennas coupled to the radios operate as aMIMO antenna.

Another MIMO system for communicating with a provided wireless device,according to various aspects of the present invention, includes at leastfour directional antennas and a quantity of radios comprising at leastthree radios. Each antenna is oriented such that a physical sector ofeach antenna substantially overlaps a physical sector of a quantity ofother antennas equal to at least the quantity of radios thereby formingrespective areas of overlap. A center of each area of overlap isoriented in a unique direction with respect to the MIMO system. Eachradio selectively couples to one respective antenna. The physicalsectors of the antennas coupled to the quantity of radios substantiallyoverlap. The quantity of radios communicate with the wireless deviceusing the respective antennas coupled to each radio. The antennascoupled to the radios operate as a MIMO antenna.

BRIEF DESCRIPTION OF THE DRAWING

Embodiments of the present invention will now be further described withreference to the drawing, wherein like designations denote likeelements, and:

FIG. 1 is a diagram of an exemplary wireless device according to thevarious aspects of the present invention;

FIG. 2 is a diagram of exemplary physical sectors;

FIG. 3 is a diagram of exemplary physical sectors that form exemplaryMIMO physical sectors;

FIG. 4 is a diagram of exemplary MIMO virtual sectors;

FIG. 5 is a diagram of an exemplary MIMO virtual sector;

FIG. 6 is a diagram of exemplary MIMO virtual sectors;

FIG. 7 is a diagram of exemplary alternate method for diagrammaticallyindicating physical sectors, MIMO physical sectors, and MIMO virtualsectors;

FIG. 8 is a diagram of communication between exemplary wireless devicesin the presence of noise sources;

FIG. 9 is a diagram of an exemplary wireless device having three radiosand three antennas for each radio;

FIG. 10 is a diagram of exemplary physical sectors that form exemplaryMIMO physical sectors;

FIG. 11 is a diagram of an exemplary wireless device having two radiogroups, each group having two radios and two antennas for each radio;

FIG. 12 is a diagram of exemplary physical sectors that substantiallyoverlap to form exemplary MIMO physical sectors;

FIG. 13 is a diagram of exemplary physical sectors that partial overlapto form exemplary MIMO virtual sectors;

FIG. 14 is a diagram of exemplary physical sectors that partial overlapto form exemplary MIMO virtual sectors;

FIG. 15 is a diagram of exemplary physical sectors that partial overlapto form exemplary MIMO virtual sectors;

FIG. 16 is a diagram of exemplary physical sectors that substantiallyoverlap to form exemplary MIMO physical sectors and exemplary MIMOphysical sectors that partially overlap to form exemplary MIMO physicalsectors;

FIG. 17 is a diagram of communication between exemplary wireless devicesin the presence of noise sources;

FIG. 18 is a diagram of communication between exemplary wireless devicesin the presence of exemplary noise sources;

FIG. 21 is a diagram of a method for forming MIMO physical sectors; and

FIG. 20 is a diagram of a method for forming MIMO physical sectors.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Wireless devices use antennas to transmit and receive radio signals.Noise sources, such as other wireless devices including wireless devicesthat transmit on the same channel, may interfere with wirelesscommunication. Conventional wireless devices use a variety of techniquesto reduce the detrimental effect of noise on communication for example,dividing the area of coverage into sectors, using directional antenna,and using multiple antennas to provide redundancy and spatial diversity.

An improved wireless device, according to the various aspects of thepresent invention includes directional antennas positioned in such a waythat the physical sectors of the antennas of the wireless device overlapand the antennas selected for communication are the antennas whosephysical sectors overlap in an area in a manner that permits theantennas to operate as a Multiple Input Multiple Output (“MIMO”)antenna.

The wireless device, according to the various aspects of the presentinvention may select for communication any suitable combination ofdirectional antennas that operate as a MIMO antenna and are oriented ina desired direction of communication. Furthermore, the wireless devicemay assign any available channel to the antennas to improve performance.

A wireless device, according to the various aspects of the presentinvention includes, for example, wireless cells, access points, wirelessclients, mobile computers, and handheld devices.

The term “physical sector” is understood to mean the area of coverage inwhich an antenna transmits and receives signals. The size and shape of aphysical sector depends on a variety of factors for example, the type ofantenna, atmospheric conditions, presence of noise sources, and physicalsurroundings. Physical sectors 58, 60 and 62 represent thetwo-dimensional shape of idealized physical sectors of directionalantennas. Physical sectors 58, 60 and 62 do not overlap in FIG. 2.Physical sectors 58, 60 and 62 substantially overlap in FIG. 3. Physicalsectors 58, 60 and 62 partially overlap in FIGS. 4 and 5.

The term “MIMO antenna” is understood to mean at least two antennas thateach transmits and/or receives signals on the same channel in the areawhere the physical sectors of the antennas overlap. Antennas may bepositioned in such a way that their physical sectors overlap. Antennaswhose physical sectors overlap in the same area may be configured tooperate as a MIMO antenna in that area. Each individual antenna of aMIMO antenna operates on the same channel (e.g., frequency, encoding, orother method of dividing the radio spectrum for communication). A MIMOantenna provides, inter alia, spatial diversity between the antennas,redundancy, and temporal diversity to reduce the effects of noise ontransmission and reception. Reducing the effects of noise permits awireless device to communicate more reliability.

Antennas that form a MIMO antenna may be oriented to use differentsignal polarization for example, horizontal, vertical, and circular.Antennas that form a MIMO antenna may be physically separated to providespatial diversity.

MIMO physical sectors are formed to provide communication with increasedimmunity to noise within the area of the MIMO physical sector. The term“MIMO physical sector” means the area where the physical sectors of theantennas that operate as a MIMO antenna overlap.

In an exemplary embodiment, referring to FIG. 3, physical sectors 58,60, and 62 substantially overlap to form MIMO physical sector 82.Physical sectors 66, 68, and 70 substantially overlap to form a MIMOphysical sector 84. In this embodiment, each MIMO physical sector has anangle of coverage of about 90 degrees. In another embodiment, referringto FIG. 6, each one physical sector 58, 60, and 62 and each one physicalsector 66, 68, and 70 has an angle of coverage of about 180 degrees,thus the resulting MIMO physical sectors 82 and 84 have an angle ofcoverage of about 180 degrees. FIG. 7 represents an alternate method fordiagrammatically representing physical sectors and MIMO physicalsectors. Physical sectors 58-62 respectively have about a 180 degreeangle of coverage and the center of each physical sector is oriented atapproximately 90 degrees (straight up on the page). Each physical sector58-62 extends from wireless device 10 to the furthest extent reached bythe respective antennas even though FIG. 7 shows gaps between thephysical sectors for clarity. The MIMO physical sectors 82 and 84 ofFIGS. 6 and 7 are equivalent; however, the diagrammatical representationof FIG. 7 provides greater clarity. Thus, MIMO physical sectors 82 and84 respectively include three substantially overlapping physical sectors58-62 and 66-70.

The physical sectors of the antennas that form a MIMO antenna are notlimited to being substantially overlapping. When physical sectors onlypartially overlap, the MIMO physical sector is the area where thephysical sectors of the antennas that form the MIMO antenna overlap.Referring to FIGS. 4 and 5, the antennas associated with physicalsectors 58-62 transmit and receive using the same channel. Area 94 isthe area where physical sectors 58, 60, and 62 overlap, thus area 94 isa MIMO physical sector. The antennas associated with physical sectors58-62 operate as a MIMO antenna in area 94. The MIMO physical sectorformed by physical sectors 66-70 is also shown in FIG. 4 as MIMOphysical sector 82.

MIMO physical sectors may be formed in a variety of ways. In oneexemplary method for forming a MIMO physical sector, referring to FIG.19, antennas are selected to operate as a MIMO antenna then the antennasare positioned in such a way that the physical sectors of the antennasoverlap. In another exemplary method for forming a MIMO physical sector,referring to FIG. 20, a plurality of antennas are positioned in such away that the physical sectors of at least some of the antennas at leastpartially overlap then at least two antennas are selected to operate asa MIMO antenna in the area where their physical sectors overlap to forma MIMO physical sector. The plurality of antennas may be positioned insuch a way that the various MIMO physical sectors that are formed areoriented in different directions. At least two antennas may be selectedto operate as a MIMO antenna in accordance with the orientation of theMIMO physical sector formed by the physical sectors of the selectedantennas. The orientation of some MIMO physical sectors may provideincreased performance over the orientation of other MIMO physicalsectors. Furthermore, the antennas that form the MIMO antenna may beassigned any available channel. Accordingly, the selected antennas, thusthe MIMO physical sector, may be assigned to a channel that providesimproved performance.

The term “MIMO virtual sector” means the area where the physical sectorsof antennas that may operate as a MIMO antenna overlap. Referring toFIG. 13, physical sectors 58-62 and 66-70 each have an angle of coverageof about 180 degrees respectively. The antennas associated with physicalsectors 58-62 and 66-70 are positioned in such a way that in area 150,physical sectors 58, 68, and 70 overlap. In area 152, physical sectors58, 60, and 70 overlap and so forth for areas 154-160. Each one area150-160 comprises a MIMO virtual sector because the antennas whosephysical sectors overlap in the area may operate as a MIMO antenna. Ifthe antennas associated with physical sectors 58, 68, and 70 areselected to form a MIMO antenna, then area 150 operates as a MIMOphysical sector. If the antennas associated with physical sectors 58,60, and 70 are selected to form a MIMO antenna, then area 152 operatesas a MIMO physical sector and so forth for the other areas. Beforeantennas are selected to form a MIMO physical sector, areas 150-160 areMIMO virtual sectors. When antennas are selected to form a MIMO antenna,the area where the physical sectors of the selected antennas overlapbecome a MIMO physical sector while the other areas remain MIMO virtualsectors. A MIMO physical sector may also be referred to as a selectedMIMO virtual sector or an active MIMO virtual sector. Any criteria maybe used to select a MIMO virtual sector for communication.

The method of positioning antennas to form MIMO virtual sectors thenselecting antennas to operate as a MIMO antenna permits the wirelessdevice to respond to changes in, inter alia, performance, noise sources,and the environment by communicating through the MIMO physical sectorthat provides increased performance.

Positioning antennas to form MIMO virtual sectors permits a wirelessdevice with fixed antenna positions to select from a variety of MIMOvirtual sectors to communicate using the MIMO physical sector thatprovides a desired level of performance. When the performance of theselected MIMO physical sector deteriorates due to, inter alia, noisesources or environmental conditions, the wireless device can selectdifferent antennas to operate as a MIMO antenna, thereby selecting adifferent MIMO virtual sector to operate as a MIMO physical sector wherethe different MIMO physical sector provides increased performance.

MIMO physical sectors permits a wireless device to communicate withincreased performance. MIMO virtual sectors permits a wireless device toselect an area to transmit and receive in accordance with the MIMOvirtual sector that provides a desired level of performance. A wirelessdevice having multiple MIMO virtual sectors may select between thevarious MIMO virtual sectors. A wireless device may select the MIMOvirtual sector that provides an increased level of performance.Positioning the antennas of a wireless device to form MIMO virtualsectors that are oriented in different directions permits the wirelessdevice to select a MIMO physical sector based on the orientation of thevirtual sector with relation to the position of noise sources.

Performance may be measure by, inter alia, throughput, data throughput,signal-to-noise ratio, reduced signal error, reduced data errors,reduced retransmission requests, reduced interference, rejection ofmultipath signals, higher transmission rates, and signal strength.

A MIMO system includes radios and antennas that may be configured toform MIMO antennas, MIMO physical sectors, and MIMO virtual sectors. AMIMO system may form a MIMO antenna using any suitable combination ofradios and antennas. A MIMO system may select any suitable MIMO physicalsector for communication. A MIMO system may have any suitable number ofMIMO virtual sectors and/or selected MIMO virtual sectors. The MIMOsystem may position its MIMO physical sectors at any orientation. TheMIMO physical sectors of a MIMO system may overlap other MIMO physicalsectors of the same MIMO system. Overlapping MIMO physical sectors ofthe same MIMO system may be assigned different channels.

A MIMO system has at least two radios and at least two antennas where atleast two radios and two antennas form a MIMO antenna. In anotherexemplary embodiment, referring to FIG. 1, a MIMO system has threeradios with two antennas interfacing with each one radio. Threeantennas, one antenna from each radio, may operate as a MIMO antenna,thereby resulting in a MIMO system having two MIMO antennas.

The present invention may employ various types of radios using any typeof communication protocol and operating at any frequency and/or with anynumber of channels suitable for the application. The present inventionmay use any variety of antennas or groups of antennas for any purposefor example, transmission, reception, noise reduction, and multipathdetection. Antennas may be positioned in any manner for example, theirphysical sectors may be overlapping and non-overlapping. Radios andantennas may operate as a MIMO system, MIMO antennas, MIMO physicalsectors, and MIMO virtual sectors. Any type of algorithm and/orprocessor may be used to enable radios and/or antennas to form andoperate as MIMO antennas. Antennas may be selected for communicationaccording to any criteria such as for example, data throughput, signalstrength, signal quality, and signal-to-noise ratio.

In one embodiment, the antennas of the wireless device are positioned toform non-overlapping MIMO physical sectors and one of thenon-overlapping MIMO physical sectors is selected for communication withother wireless devices. In another embodiment, the antennas of thewireless device are positioned to form overlapping MIMO virtual sectorsand some of the MIMO virtual sectors are selected for communication withother wireless devices.

The antennas that form a MIMO antenna may be used in any manner totransmit and/or receive signals for example, any number of antennas thatoperate as the MIMO antenna may transmit only, receive only, andtransmit and receive signals.

In an exemplary embodiment, referring to FIG. 1, antennas 34, 36, and38, with their associated radios, form a MIMO antenna in which eachantenna 34, 36, and 38 transmits and receives the same signals. Inanother embodiment, antennas 34-38 form a MIMO antenna in which antenna34 transmits, antenna 36 receives only, and antenna 38 transmits andreceives. Different MIMO antenna configurations may provide differentcommunication characteristics. For example, a configuration where allantennas of the MIMO antenna transmit and receive the same informationmay provide increased error correction. A configuration where antennastransmit and/or receive different information may provide increased datathroughput. In an configuration where each antenna of the MIMO antennareceives some version of the same signal, the information content of thevarious signal versions received by the antennas of the MIMO antenna maybe highly similar and/or less similar depending on environmentalconditions for example, the presence of noise sources, multipathreflections, and spatial diversity of the antennas. Advanced algorithmsmay be used to process the signal received by each antenna that form theMIMO antenna to construct a resultant receive signal that contains asmuch of the receive signal information as can be extracted. The antennasof a MIMO antenna may be configured to receive signals from a commonsource by positioning the antennas such that their physical sectorsoverlap.

The number of antennas used to form a MIMO physical sector and theoverlap of the physical sectors of the antennas may affect performance.For example, referring to FIGS. 1 and 5, area 90 receives coverage fromonly physical sector 62, thus communications within area 90 aretransmitted and received by only antenna 38. Likewise, area 98 receivescoverage only from physical sector 60 and antenna 36. Even when antennas36 and 38 are selected to operate as a MIMO antennas, areas 90 and 98are not MIMO physical sectors because only one antenna operates in thearea. When only one antenna of the antennas selected to operate as aMIMO antenna transmits and receives in an area, the performance may notbe as high as in the areas where the physical sectors of the antennasoverlap to form a MIMO physical sector. Areas 92 and 96 receive coveragefrom physical sectors 58, 62 and 58, 60 respectively. Areas 92 and 96are MIMO physical sectors because at least two antennas operate as aMIMO antenna in the areas. Communication using at least two antennas ofthe antennas selected to operate as a MIMO antenna may improveperformance. Area 94, a MIMO physical sector formed by the overlap ofthe physical sectors of three antennas, receives coverage from physicalsectors 58, 60 and 62 and their related antennas 34-38. Antennas 34-38operate as a MIMO antenna, thus reception and/or transmission throughall three antennas in area 94 may provide higher performance thanreception and/or transmission through areas 90-92 and 96-98. The MIMOphysical sector in area 94 is most likely to provide improvedperformance because all antennas of the MIMO antenna communicate in area94.

MIMO physical sectors formed using directional antennas may useconventional antenna select methods to reduce interference from noisesources. For example, referring to FIGS. 1 and 8, wireless device 10comprises processor 12, radios 18-22, RF switches 26-30, and antennas34-38 and 42-46 where two antennas interfacing with each one RF switchrespectively. Antennas 34-38 and 42-46 operate as a first MIMO antennaand a second MIMO antenna respectively. Radios 18-22 use the 802.11a/b/g/n communication protocols. Antenna physical sectors 58-62,associated with antennas 34-38 respectively, substantially overlap toform MIMO physical sector 82. Antenna physical sectors 66-70, associatedwith antennas 42-46 respectively, substantially overlap to form MIMOphysical sector 84. In this embodiment, each radio is set to the samechannel. The physical sectors and the MIMO physical sectors 82-84 extendfarther than shown in FIG. 8 to enable wireless device 10 to communicatewith wireless device 102 and receive interference from noise sources 106and 108. Wireless device 10 uses RF switches 26-30 to select betweenantennas 34-38 and 42-46. In this embodiment, the RF switches selectbetween one of two groups of antennas; either antennas 34-38 or antennas42-46 are selected, thus only one MIMO physical sector, either 82 or 84,is active at any given time. In the embodiment and the scenariodescribed in FIG. 8, wireless device 10 selects MIMO antennas physicalsector 84 to reduce interference from noise sources 106 and 108 whilecommunicating with wireless device 102. Wireless device 104 of FIG. 8may also be implemented using MIMO physical sectors similar to those ofwireless device 10. Wireless device 104 may select the MIMO physicalsector that provides the best performance while communicating withwireless device 102 and reduces interference from noise source 110.

In another embodiment of a MIMO system, referring to FIG. 9, wirelessdevice 10 comprises a processor 12, three radios 18-22, three RFswitches 26-30, and three antennas interfacing with each RF switch.Antennas 34-38, 42-46, and 50-54 may have any angle of coverage, beoriented in any direction, form MIMO antennas, and form MIMO virtualsectors in any manner. In an exemplary embodiment, referring to FIG. 10,each antenna 34-38, 42-46, and 50-54 has an angle of coverage of about120 degrees. Antennas 34-38 are oriented so that their associatedphysical sectors, 58-62 respectively, substantially overlap to form MIMOphysical sector 82. Antennas 42-46 are oriented so that their associatedphysical sectors, 66-70 respectively, substantially overlap to form MIMOphysical sector 84. Antennas 50-54 are oriented so that their associatedphysical sectors, 74-78 respectively, substantially overlap to form MIMOphysical sector 86. Physical sectors 58-62, 66-70, and 74-78 areoriented such that the center of MIMO physical sectors 82, 84, and 86are respectively oriented at about 60, 180, and 300 degreesrespectively. In this embodiment, the MIMO physical sectors do notsubstantial overlap. Each radio is set to the same channel, thus theMIMO physical sectors 82-86 each use the same channel. The wirelessdevice embodiment of FIGS. 9 and 10 may also be used to reduceinterference with noise sources by selected one of the three MIMOphysical sectors for communication.

In another embodiment, not shown, wireless device 10 comprises aprocessor, four radios, an RF switch interfacing with each one radio,and four directional antennas interfacing with each one RF switch. Eachantenna has an angle of coverage of about 90 degrees. The physicalsectors of one antenna from each RF switch substantially overlap to forma MIMO physical sector resulting in a MIMO system having four MIMOvirtual sectors. Each MIMO physical sector receives coverage from eachone of the four radios. The physical sectors of the antennas areoriented in such a way that the MIMO physical sectors do not overlap andthe MIMO physical sectors provide a combined angle of coverage of about360 degrees. All radios are set to the same channel.

In another embodiment, not shown, wireless device 10 comprises aprocessor, two radios interfacing with the processor, an RF switchinterfacing with each one of the radios, and three directional antennasinterfacing with each one RF switch. Each antenna has an angle ofcoverage of about 120 degrees. The physical sectors of one antenna fromeach one RF switch substantially overlap to form a MIMO physical sectorresulting in a MIMO system having three MIMO virtual sectors. Each MIMOphysical sector receives coverage from each one of the two radios. Thephysical sectors of the antenna are oriented in such a way that the MIMOphysical sectors do not overlap and the MIMO physical sectors provide acombined angle of coverage of about 360 degrees. All radios are set tothe same channel.

In another embodiment, not shown, wireless device 10 comprises aprocessor, two radios interfacing with the processor, an RF switchinterfacing with each one of the radios, and “N” directional antennasinterfacing with each one RF switch. Each antenna has an angle ofcoverage of about 360 degrees divided by N. Two antennas, one from eachRF switch, form a MIMO antenna, thereby forming N MIMO antennas. Thephysical sectors of the antennas that form each MIMO antennasubstantially overlap to form N MIMO physical sectors. The MIMO physicalsectors are oriented in such a way that the MIMO physical sectors do notsubstantially overlap, thereby providing a combined angle of coverage ofabout 360 degrees. All radios are set to the same channel.

Radios, antennas, and MIMO physical sectors are not limited to using asingle channel for communication or to forming MIMO physical sectorsthat are substantially non-overlapping. Radios may be grouped to provideMIMO physical sectors that use different channels. MIMO physical sectorsthat communicate on different channels may be positioned to overlap.Overlapping MIMO physical sectors that use different channels maysimultaneously communicate less mutual interference.

In one embodiment, referring to FIG. 11, wireless device 10 comprises aprocess 12, controllers 14, 16 interfaces with processor 10, two radios18, 20 interface with controller 14 thereby forming a first radio group,two radios 22, 24 interface with controller 16 thereby forming a secondradio group, an RF switch 26, 28, 30, 32 interfaces with radio 18, 20,22, 24 respectively, antennas 34-48 interface with the RF switches insuch a manner that two antennas interface with each one RF switch. Theantennas may form MIMO antennas any manner; however, forming MIMOantennas using antennas from the same group enables MIMO physicalsectors from different groups to operate on different channels.

In one embodiment, antennas 34 and 36 form a first MIMO antenna.Antennas 42 and 44 form a second MIMO antenna. The first and second MIMOantennas belong to the first radio group. Antennas 38 and 40 form athird MIMO antenna. Antennas 46 and 48 form a fourth MIMO antenna. Thethird and fourth MIMO antennas belong to the second radio group. Inanother embodiment, antennas 34-40 form a first MIMO antenna andantennas 42-48 form a second MIMO antenna.

The antennas and their respective physical sectors may have any angle ofcoverage and be oriented in any direction. The antennas of the variousgroups may form MIMO antennas in any manner. The resulting MIMO physicalsectors may be overlapping or non-overlapping. In an exemplaryembodiment, antennas 34, 36, 38, 40, 42, 44, 46, and 48 and theirrespective physical sectors 58, 60, 62, 64, 66, 68, 70, and 72 each havean angle of coverage of about 180 degrees. Referring to FIGS. 11 and 12,physical sector 58 substantially overlaps physical sector 60 to formMIMO physical sector 82. Physical sectors 62 and 64 substantiallyoverlap, 66 and 68 substantially overlap, and 70 and 72 substantiallyoverlap to form MIMO physical sectors 84, 86, and 88 respectively. Thecenter of the angles of coverage of antennas 34, 36 and 38, 40 areoriented at about 90 degrees (e.g., up the page), thus MIMO physicalsectors 82 and 84 overlap. The center of the angles of coverage ofantennas 42, 44 and 46, 48 are oriented at about 270 degrees (e.g., downthe page), thus MIMO physical sectors 86 and 88 substantially overlap.Radios 18 and 20 belong to the first radio group and radios 22 and 24belong to the second radio group. Assigning channel C1 to the firstradio group and channel C2 to the second radio group results in MIMOphysical sectors 82 and 86 using channel C1 and MIMO physical sectors 84and 88 using channel C2. Thus, the channel assignment, the antennaorientation, and the MIMO antenna configurations provide overlappingMIMO physical sectors that use different channels. Referring to FIG. 12,MIMO physical sector 82 is assigned to Cl, MIMO physical sector 84 isassigned to C2, and MIMO physical sector 82 substantially overlaps MIMOphysical sector 84. Because MIMO physical sectors 82 and 84 are assigneddifferent channels, they may communicate with different wireless devicessimultaneously with less mutual interference. MIMO physical sectorsformed using antennas from different radio groups enables the MIMOphysical sectors to overlap, be assigned different channels, andcommunicate simultaneously. MIMO antennas of the same radio group usethe same channel. Interference between MIMO physical sectors formedusing antennas from the same group may be reduced by, for example,positioning the MIMO physical sectors in such a way that they do notoverlap and communicating using only one MIMO physical sector from thesame group at any one time.

In another embodiment, referring to FIG. 11, each one antenna 34-48 hasa physical sector with an angle of coverage of about 90 degrees.Antennas are organized, as described above, to form four MIMO antennas.Antenna physical sectors are positioned such that the center of theangle of coverage for antennas pairs 34 and 36, 38 and 40, 42 and 44,and 46 and 48 and their respective physical sectors are oriented at 45,135, 225, and 315 degrees respectively. Channel C1 is assigned to thefirst group radios and channel C2 is assigned to the second groupradios. The resulting four MIMO physical sectors are positioned to notsubstantially overlap and adjacent MIMO physical sectors are assigned adifferent channel. One MIMO physical sector from the first radio groupand one MIMO physical sector from the second radio group may operatesimultaneously.

The antennas of wireless device 10 may be oriented to form MIMO virtualsectors. MIMO virtual sectors may have any angle of coverage and beoriented in any manner. A MIMO virtual sector may be selected forcommunication to decrease interference. In one embodiment, referring toFIGS. 1 and 13, antennas 34-38 and 42-46 have an angle of coverage ofabout 180 degrees. Antennas 34, 36, 38, 42, 44, 46 and the center of theangle of coverage of their respective physical sectors 58, 60, 62, 66,68, 70 are oriented at 90, 150, 210, 270, 300, and 30 degreesrespectively. The area between 0 and 60 degrees, marked as area 150 inFIG. 13, is covered by physical sectors 58, 68, and 70. Antennas 34, 44,and 46 may function together as a MIMO antenna to transmit signals toand receive signals from any wireless device within area 150. Areas 152,154, 156, 158, and 160 are respectively positioned between about 60-120degrees, about 120-180 degrees, about 180-240 degrees, about 240-300degrees, and about 300-0 degrees and are serviced respectively byantennas 34, 36, and 46; 34, 36 and 38; 42, 36 and 38; 42, 44 and 38;and 42, 44 and 46. Each one area 150-160 comprises a MIMO virtualsector.

In an exemplary embodiment, referring to FIGS. 1 and 13, area 150operates as a MIMO physical sector by forming a MIMO antenna usingantennas 34, 44, and 46. Area 152 operates as a MIMO physical sector byforming a MIMO antenna using antennas 34, 36, and 46, and so forth forareas 154-160. In this embodiment, areas 158 and 160 may not be combinedto operate as a MIMO physical sector because area 158 requires antennas42, 44, and 38 to form a MIMO antenna while area 160 requires antennas42, 44, and 46 to form a MIMO antenna. Because RF switch 30 selects onlyone antenna at a time, MIMO physical sectors, for this embodiment, arelimited to any combination of any one antenna associated with each RFswitch. In this embodiment, wireless device 10 may select andcommunicate through any one MIMO virtual sector at any given time. Themethod of selecting the MIMO virtual sector consists of setting the RFswitches to select the antennas that service the desired MIMO virtualsector. In another embodiment, an RF switch with its associated antennasmay be replaced by a phased array. Antenna elements of each phased arraymay form MIMO antennas.

Antennas may be oriented in any manner to form MIMO virtual sectors ofany size. In an exemplary embodiment, referring to FIG. 13, each MIMOvirtual sector 150-160 has an angle of coverage of about 60 degrees. Inanother embodiment, referring to FIG. 14, MIMO virtual sectors 150, 152,154, 156, 158, and 160 lie between 0-30 degrees, 30-60 degrees, 60-180degrees, 180-210 degrees, 210-240 degrees, and 240-0 degreesrespectively. In another embodiment, referring to FIG. 15, each MIMOvirtual sector has an angle of coverage of about 40 degrees. MIMOvirtual sectors 150-166 lie between 0-40 degrees, 40-80 degrees, 80-120degrees, 120-160 degrees, 160-200 degrees, 200-240 degrees, 240-280degrees, 280-320 degrees, and 320-0 degrees respectively. In anotherembodiment, referring to FIGS. 11 and 18, each MIMO virtual sector hasan angle of coverage of about 90 degrees. Channel C1 is assigned to thefirst group radios and channel C2 is assigned to the second groupradios. Antenna pairs 34 and 36, 38 and 40, 42 and 44, and 46 and 48respectively form MIMO antennas. MIMO virtual sectors formed by antennas34, 36 and 42, 44 extend from 0-180 and 180-0 degrees respectively andare assigned channel C1. MIMO virtual sectors formed by antennas 38, 40and 46, 48 extend from 90-270 and 270-90 degrees respectively and areassigned channel C2. The MIMO virtual sectors are positioned to formareas 150-156 which each receive coverage from two MIMO virtual sectorsthat operate on different channels.

A wireless device may select and communicate through a MIMO virtualsector to improve performance. A wireless device may use any criteriafor selecting a MIMO virtual sector for communication such as, forexample, the presence of noise sources, noise source channels used,signal-to-strength ratio, direction of primary data flow, signalquality, signal strength, and data throughput.

In one embodiment, referring to FIGS. 9 and 17, wireless device 10desires to communicate with wireless device 102. Wireless device 10successively enables each antenna combination that forms each MIMOvirtual sector 150-160. Through each MIMO virtual sector, wirelessdevice 10 measures its ability to communicate with wireless device 102.Through at least MIMO virtual sector 150, wireless device 10 detects thepresence of noise source 110. Through at least MIMO virtual sectors 154and 156, wireless device 10 detects the presence of noise sources 106and 108 respectively. While communicating with wireless device 102,wireless device 10 may reduce interference from noise sources 106 and108 by selecting and communicating through MIMO virtual sector 150. Inthe embodiment of wireless device 10 shown in FIGS. 1 and 17, areasadjacent to the selected MIMO virtual sector have at least one antennain common, thus selecting a MIMO virtual sector does not disable allcommunication in other sectors, but communication within the selectedMIMO virtual sector may provide increased performance than adjacentareas because it transmits and/or receives using all the antennas thatform the MIMO antenna.

Referring still to FIGS. 1 and 17, wireless device 10 may reduceinterference from noise source 110 by selecting a channel that isdifferent from the channel used by noise source 110. In the event thatwireless device 102 cannot switch to a channel that is not used by noisesource 110, communication with wireless device 102 may proceed usingMIMO virtual sector 150 if it provides a desired level of performance. Awireless device may select any MIMO virtual sector that provides adesired level of performance. In this embodiment, wireless device 10 mayselect MIMO virtual sector 152 to communicate with wireless device 102.Wireless device 10 may detect less interference from noise source 110through MIMO virtual sector 152 than it detects through MIMO virtualsector 150, but wireless device 10 may also receive a less desirablesignal from wireless cell 102. In the event that wireless device 10desires to communicate with wireless device 104 and noise sources 106,108, and 110 all operate on the same channel as wireless device 104,wireless cell 10 may reduce interference from the noise sources byselecting MIMO virtual sector 160 for communicating with wireless device104. A wireless device may select and use any MIMO virtual sector forany duration of time. A wireless device may switch from using one MIMOvirtual sector to using any other MIMO virtual sector at any time andfor any purpose. In an exemplary embodiment, referring to FIG. 17,wireless device 10 switches between MIMO virtual sectors 150 and 160 tocommunicate with wireless devices 102 and 104 respectively.Additionally, a wireless device may transmit through one MIMO virtualsector and receive through a different MIMO virtual sector. In anotherembodiment, referring to FIGS. 11 and 18, wireless device 10 may selectthe MIMO virtual sector that provides a desired level of communicationfor each area. Additionally, wireless device 10 may communicate with twowireless devices 104 and 120, both in area 156, simultaneously ondifferent channels; for example, wireless device 104 communicates usingchannel C1 while wireless device 120 communicates using channel C2.

Unless contrary to physical possibility, the inventor envisions themethods and systems described herein: (i) may be performed in anysequence and/or combination; and (ii) the components of respectiveembodiments combined in any manner.

Although there have been described preferred embodiments of this novelinvention, many variations and modifications are possible and theembodiments described herein are not limited by the specific disclosureabove, but rather should be limited only by the scope of the appendedclaims.

1. A MIMO system for communicating with a provided wireless device, theMIMO system comprising: at least three directional antennas; and atleast two radios; wherein: each antenna is oriented such that a physicalsector of each antenna substantially overlaps a physical sector of atleast one other antenna thereby forming respective areas of overlap; acenter of each area of overlap is oriented in a unique direction withrespect to the MIMO system; each radio selectively couples to onerespective antenna; the physical sectors of the antennas coupled to theradios substantially overlap; the at least two radios communicate withthe wireless device using the respective antennas coupled to each radio;the antennas coupled to the radios operate as a MIMO antenna.
 2. TheMIMO system of claim 1 wherein the at least three antennas arecollocated such that a physical sector of each antenna extends outwardlyfrom the MIMO system.
 3. The MIMO system of claim 1 wherein the antennascoupled to the at least two radios communicate using a same channel. 4.The MIMO system of claim 1 wherein: the antennas coupled to the at leasttwo radios communicate using a same channel; and each antenna has adifferent polarization.
 5. A MIMO system for communicating with aprovided wireless device, the MIMO system comprising: at least fourdirectional antennas; and a quantity of radios comprising at least threeradios; wherein: each antenna is oriented such that a physical sector ofeach antenna substantially overlaps a physical sector of a quantity ofother antennas equal to at least the quantity of radios thereby formingrespective areas of overlap; a center of each area of overlap isoriented in a unique direction with respect to the MIMO system; eachradio selectively couples to one respective antenna; the physicalsectors of the antennas coupled to the quantity of radios substantiallyoverlap; the quantity of radios communicate with the wireless deviceusing the respective antennas coupled to each radio; and the antennascoupled to the radios operate as a MIMO antenna.
 6. The MIMO system ofclaim 5 wherein the at least three antennas are collocated such that aphysical sector of each antenna extends outwardly from the MIMO system.7. The MIMO system of claim 5 wherein the antennas coupled to thequantity of radios communicate using a same channel.
 8. The MIMO systemof claim 5 wherein: the antennas coupled to the quantity of radioscommunicate using a same channel; and each antenna has a differentpolarization.